Seat with surface material having multilayer having different hardness and method for manufacturing the same

ABSTRACT

A seat avoiding crumples of a surface material covering a cushioning body thereof, giving a comfortable soft feeling for a person who sits thereon and having such a hardness that a weight of the person can be supported. A seat (1) comprising a surface material (2) and a cushioning body having a shape corresponding to an outline of the seat. The cushioning body composing of a first cushioning body (6) integrated in one with at least a part of the surface material and a second cushioning body (10) underlying the first cushioning body.

TECHNICAL FIELD

The present invention relates to a seat typically used for a car andalso relates to a seat used for an industrial vehicle such as aforklift, a tractor and the like and a seat of a chair used in an officeor as a furniture. In particular, the present invention relates to aseat in which a surface material is integrated in one with a cushioningbody thereof.

BACKGROUND OF THE ART

FIG. 7 shows a seat as typically used for a car composing a surfacematerial 71 and a cushioning body 77 in accordance with the art. Thesurface material 71 composes a side surface member 72, a circumferentialsurface member 73 and a central surface member 74, and the side surfacemember 72, the circumferential surface member 73 and the central surfacemember 74 are corresponding to a side portion, a circumferential portionand a central portion of the seat, respectively. Each member of thesurface material 71 is cut from a flat sheet material, and the surfacematerial 71 is formed by stitching those members 72, 73, 74 so that ashape of the surface material 71 can be corresponding to a threedimensional shape of the seat.

The cushioning body 77 is covered with the surface material 71 havingthe same outline as the cushioning body 77. Then, the surface material71 is connected with the cushioning body 77 by connecting a wire 78,which is provided in a gap formed in the cushioning body 77, and anotherwire 76, which is provided with a band cloth 75 stitched with thecentral surface member 74 and the circumferential surface member 73,through a hog-ring so that the surface material 71 can not be floated.The seat of the art is assembled in accordance with a manner asmentioned in the above.

It takes much time to cut a sheet material into those members of thesurface material. Recently, a shape of a surface material used for aseat has been complicated, and in order to form such a surface material,the sheet material must be cut into members of the surface materialhaving several shapes. Also, it is not suitable for mass production toconnect the surface material 71 and the cushioning body 77 by use of thehog-ring, because workers must pay much time to assemble the surfacematerial 71 and the cushioning body 77 in a work shop for carrying outsuch an assembling line work without a break.

In addition, when a person sits on the seat, the surface material istensioned by a weight of the person. In the art, several textilematerials typically used for the surface material can not be restored toan original state thereof when the person is away from the seat. Thus,the surface material is crumpled, and an external view as a quality ofthe seat is injured thereby.

In order to solve those problems, in a conventional technique, as shownin FIG. 7, a slab material 79 of an urethane foam having an excellentresiliency is bonded on a back surface of the surface material, and athin textile material 80 is bonded on another surface of the urethanefoam, in order to enhance resilient characteristics of the surfacematerial.

However, it takes much time to fabricate such a surface material, and asa result, the surface material is expensive.

Also, for a seat used for a vehicle and a chair used in an office or asa furniture and the like (hereinafter simply written by a seat), ingeneral, a resiliency is required to make a person comfortable when theperson sits on the seat, and an appropriate hardness is also required tosupport a weight of the person.

In addition, in order to improve a shape-maintainability of the seat andan external view as a quality of the seat, it is desired to harden aside portion of the cushioning body of the seat.

However, in the seat composed and manufactured by according to the art,it is difficult to freely and partially control the hardness of thecushioning body thereof.

Therefore, an object of the present invention is to provide a seatwherein a surface material of the seat is integrated in one with acushioning body thereof and a method for manufacturing such a seat.

Another object of the present invention is to provide a seat comprisinga cushioning body composing of an upper layer and a lower layer whereinthe upper layer which contacts with a person through a surface materialis appropriately soft and the lower layer for supporting a weight of theperson is appropriately hard, and is to provide a method formanufacturing such a seat.

Still another object of the present invention is to provide a seatcomprising a cushioning body composing of an upper layer and a lowerlayer wherein a hardness of the upper layer is partially different, andis to provide a method for manufacturing such a seat.

Yet another object of the present invention is to provide a seatcomposing a surface material and a cushioning body integrated in onewith the surface material wherein a constitution of the surface materialis simplified, and is to provided a method for manufacturing such aseat.

DISCLOSURE OF THE INVENTION

In order to achieve those objects, a seat according to the presentinvention comprises a surface material and a cushioning body which has ashape generally corresponding to an outline of the seat and is coveredwith the surface material, and the cushioning body is composed of afirst cushioning body and a second cushioning body which underlies as abase of the cushioning body. The first cushioning body is integrated inone with the second cushioning body, so that the first cushioning bodycan be underlain by the second cushioning body, by introducing a liquidfoamable mixture for forming the first cushioning body on the secondcushioning body and then integrally pressurizing the liquid foamablemixture together with the surface material positioned thereon when a gasreaction of the liquid foamable mixture has been completed but theliquid foamable mixture is still in an elastic flowing condition so thatthe first cushioning body can be integrated in one with the surfacematerial through a back surface thereof and also integrated in one withthe second cushioning body through an upper surface thereof.

The hardness of the first cushioning body can be partially controlled byadjusting a compressibility when the gas reaction has been completed butthe liquid foamable mixture is still in an elastic flowing condition.

A method according to the present invention for manufacturing a seatcomprising a surface material and a cushioning body integrated in onewith the surface material, wherein the cushioning body has a shapegenerally corresponding to an outline of the seat and is composed of afirst cushioning body and a second cushioning body which underlies thefirst cushioning body, comprises steps of:

introducing a liquid foamable mixture for forming the first cushioningbody on a surface of the second cushioning body;

facing at least a part of a back surface of the surface material to theliquid foamable mixture introduced on the surface of the secondcushioning body; and

pressurizing and compressing the liquid foamable mixture, which isintroduced on the surface of the second cushioning body, together withthe surface material between a pressure applying mold having a shape ofa central portion of the seat and positioned above the surface materialand the second cushioning body when a gas reaction of the liquidfoamable mixture has been completed but the liquid foamable mixture isstill in an elastic flowing condition.

In the step of facing, it is desirable that the liquid foamable mixtureintroduced on the surface of the second cushioning body places betweenthe surface material and the second cushioning body so that the secondcushioning body can be covered with the surface material.

An alternative method according to the present invention formanufacturing a seat comprising a surface material and a cushioning bodyintegrated in one with the surface material, wherein the cushioning bodyhas a shape generally corresponding to an outline of the seat and iscomposed of a first cushioning body and a second cushioning body whichunderlies the first cushioning body, comprises steps of:

introducing a liquid foamable mixture for forming the first cushioningbody on a surface of the second cushioning body;

positioning a central surface portion of the surface material in apressure applying mold which has a shape corresponding to a shape of acentral portion of the seat and is positioned on the second cushioningmaterial;

facing the central surface portion positioned in the pressure applyingmold to the liquid foamable mixture introduced on the surface of thesecond cushioning body; and

pressurizing and compressing the liquid foamable mixture, which isintroduced on the surface of the second cushioning body, between thepressure applying mold positioned the surface material and the secondcushioning body when a gas reaction of the liquid foamable mixture hasbeen completed but the liquid foamable mixture is still in an elasticflowing condition.

An another alternative method according to the present invention formanufacturing a seat comprising a surface material and a cushioning bodyintegrated in one with the surface material, wherein the cushioning bodyhas a shape generally corresponding to an outline of the seat and iscomposed of a first cushioning body and a second cushioning body whichunderlies the first cushioning body, comprises steps of:

introducing a liquid foamable mixture for forming the first cushioningbody on a surface of the second cushioning body;

positioning a central surface portion of the surface material in apressure applying mold, which has at least one suction hole and has ashape corresponding to a shape of a central portion of the seat, bysucking the central surface portion through the suction hole;

facing the central surface portion positioned and sucked in the pressureapplying mold to the liquid foamable mixture introduced on the surfaceof the second cushioning body; and

pressurizing and compressing the liquid foamable mixture introduced onthe surface of the second cushioning body between the pressure applyingmold positioned and sucked the surface material and the secondcushioning body when a gas reaction of the liquid foamable mixture hasbeen completed but the liquid foamable mixture is still in an elasticflowing condition.

It is desirable that the hardness of the first cushioning body ispartially controlled by adjusting a compressibility applied for theliquid foamable mixture when the gas reaction of the liquid foamablemixture has been completed but the liquid foamable mixture is still inan elastic flowing condition. It is desirable that the compressibilityis adjusted by partially adjusting a space defined between the pressureapplying mold and the second cushioning body, and such a partialadjustment can be achieved by introducing the liquid foamable mixture onthe second cushioning body so that a thickness of a layer formed byintroducing the liquid foamable mixture can be the same over the secondcushioning body and then pressurizing and compressing the layer.

It is desirable that the first and second cushioning bodies are moldedfrom a reactive foamable resin of a polyurethane foam or a polyureafoam.

It is desirable that the surface material is composed of a centralsurface portion and a side surface portion successively connected withthe central surface portion, and the central surface portion isintegrated in one with the first cushioning body and the side surfaceportion covers sides of the second cushioning body.

The hardness of the first cushioning body can be different from that ofthe second cushioning body in accordance with the purpose of use of aseat.

A textile material of a woven fabric or a knitted fabric, a leather, asynthetic leather or a PVC leather can be used for the surface material,and it is desirable to provide a slab material of an urethane foam or aplastic film on a back surface of the surface material. Also, it isdesirable to provide a plastic film on a back surface of the sheetmaterial of the slab urethane foam provided on the back surface of thesurface material.

A seat according to the present invention is formed of a surfacematerial integrated in one with a cushioning body, and thereby thesurface material can be restored into the original state by theresiliency of the cushioning body when a weight of a person who sits onthe seat is released.

Moreover, the surface material is integrated in one with the firstcushioning body having a shape corresponding to an outline of the seat,and thereby it is unnecessary to cut and stitch so that a shape of thesurface material can be corresponding to an outline of the seat.

Furthermore, a hardness of the first cushioning body can be partiallycontrolled by adjusting a space defined between the pressure applyingmold and the second cushioning body and then by pressurizing andcompressing. The holdability of the seat can be improved by hardening acircumferential portion of the seat so that a main portion of the seatcan be soft.

Also, a hardness of the second cushioning body is selectable independentof that of the first cushioning body so that such a hardness that aweight of a person who sits thereon can be supported can be given to thesecond cushioning body.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross sectional view of a seat according to the presentinvention.

FIG. 2 is a cross sectional view of a mold composing an upper and alower molds for molding a second cushioning body.

FIG. 3 is a cross sectional view of a second cushioning body molded byusing a mold shown in FIG. 2.

FIG. 4 is a cross sectional view of an arrangement of a pressureapplying mold, a surface material, a mixture and a second cushioningbody in order to mold a first cushioning body in accordance with amethod of the present invention.

FIG. 5 is a cross sectional view of an arrangement of a pressureapplying mold having step portions, a surface material, a mixture and asecond cushioning body in order to mold a first cushioning body inaccordance with an alternative method of the present invention.

FIG. 6 is a cross sectional view of an arrangement of a pressureapplying mold having suction holes, a surface material, a mixture and asecond cushioning body in order to mold a first cushioning body inaccordance with an another alternative method of the present invention.

FIG. 7a is a cross sectional view of a surface material used for a seatof the art, and FIG. 7b is a cross sectional view of a cushioning bodyused for the seat of the art.

BEST MODE FOR CARRYING OUT THE INVENTION

With referring to drawings, embodiments of the present invention aredescribed.

FIG. 1 is a cross sectional view of a seat manufactured by a methodaccording to the present invention. The seat 1 is composed of a surfacematerial 2, a first cushioning body 6 as an upper layer and a secondcushioning body 10 as a lower layer which underlies the first cushioningbody 6. An outline of the seat is defined by all of those components.

The surface material 2 is composed of a central surface portion 3 (whichforms a central portion of the seat), side surface portions 4, 5continued from sides of the central surface portion and covering thesecond cushioning body 10. As described in the followings, the centralsurface portion 3 is integrated in one with the first cushioning body 6through a back surface thereof, and the first cushioning body isintegrated in one with the second cushioning body 10.

The surface material 2 can be composed by stitching memberscorresponding to the central surface portion 3 and the side surfaceportions 4, 5, separately cut from a sheet material as mentioned in theseat shown in FIG. 1. Alternatively, only one member corresponding tothe portions 3, 4, 5 can be used as the surface material 2.

A material used for the surface material 2 is not limited, and thesurface material 2 may be a textile material of a woven fabric, aknitted fabric and the like, or a synthetic leather, a leather or a PVCleather, used for a surface material of a seat in general.

The first cushioning body 6 is formed of a central body portion 7 andcircumferential body portions 8, 9 continued to both sides of the firstcushioning body 6. The central body portion 7 has a generally uniformthickness and the circumferential body portions 8, 9 have a graduallythinned thickness.

The first cushioning body 6 is formed of a foamed body such as apolyurethane foam which is typically used as a foamed body.Alternatively, the first cushioning body 6 can be formed of a reactivefoamable resin such as a polyurea foam and the like.

While a hardness of the first cushioning body 6 can be uniform over thefirst cushioning body 6, it is more desirable that the circumferentialbody portions 8, 9 are hardened more than that of the central bodyportion by according to a method for manufacturing the first cushioningbody 6 as mentioned in the followings, so that a holdability to a personwho sits the seat can be improved and an outline of the seat can bemaintained.

The second cushioning body 10 as a base of the seat has a shapegenerally corresponding to a shape of the seat and is integrated in onewith the first cushioning body 6 by according to a method mentioned inthe followings so that the first cushioning body 6 can be underlain bythe second cushioning body 10.

As well as the first cushioning body 6, the second cushioning body 10 isformed of a foamed body of a polyurethane foam, or a reactive foamableresin such as a polyurea foam or the like.

It is desirable that the first cushioning body 6 is soft and the secondcushioning body 10 is hard, so that the first cushioning body 6 can givea comfortable feeling for a person who sits on a seat and so that thesecond cushioning body 10 can support a weight of the person, canimprove the holdability and can maintain an outline of the seat.Alternatively, if the cushionability is required for the seat, thehardness of the second cushioning body can be reduced to be soft.

We now consider a method for manufacturing a seat according to thepresent invention.

The second body 10 as a base of the seat can be molded by according to aconventional method. Firstly, means (herein called as a foaming mold)for molding the second cushioning body 10 are provided and comprise anupper mold 21 and a lower mold 22 as shown in FIG. 2. An inner surface23 of the upper mold 21 has a shape corresponding to a bottom shape ofthe second cushioning body 10, and an inner surface 24 of the lower mold22 has preferably a flat surface or a central convex portion to form thefirst cushioning body 6 on the second cushioning body 10. When the uppermold 21 and the lower mold 22 are closed, a shape of a space 25 definedbetween those molds 21, 22 is corresponding to a three dimensional shapeof the second cushioning body 10.

A liquid foamable mixture of a polyurethane foam is introduced in thelower mold 22. Then, the upper mold 21 and the lower mold 22 are closed,and the second cushioning body 10 is molded by foaming and molding themixture between them, as shown in FIG. 3. The second cushioning body 10is used as a lower mold, as formed the first cushioning body 6 on thesecond cushioning body 10 by using means of an upper and a lower molds,as described in the followings.

One embodiment of a method according to the present invention formolding the first cushioning body is shown in FIG. 4.

An upper mold (hereinafter written by a pressure applying mold) 31 forapplying a pressure is positioned above the second cushioning body 10formed by according to the technique mentioned in the above. A threedimensional shape of the first cushioning body 6 is defined between anlower surface (hereinafter written by a pressure applying surface) 32 ofthe pressure applying mold 31 and an upper surface 11 (which is formedby the inner surface 34 of the lower mold 22) of the second cushioningbody 10.

Then, as shown in FIG. 4, a liquid foamable mixture 33 of a polyurethanefoam is introduced to form a layer of the liquid foamable mixture 33 ona whole area of the upper surface 11 of the second cushioning body 10.The liquid foamable mixture 33 can be introduced by using means forspraying the mixture thereon.

While a liquid mixture of a reactive foamable resin of a polyurethanefoam is used in this embodiment, a liquid mixture of a reactive foamableresin of a polyurea foam can be used.

Meanwhile, a surface material 2 composing a central surface portion 3and side surface portions 4, 5 successively connected with both sides ofthe central surface portion 3 by stitching those portions 3, 4, 5 isdisposed in such an arrangement that the central surface portion 3 ispositioned on the liquid mixture 33 formed as a layer on the uppersurface 11 and the side surface portions 4, 5 are positioned on bothsides of the second cushioning body 10. The central surface portion 3 ofthe surface material 2 is adjusted to the pressure applying surface 32of the pressure applying mold 31.

Then, the pressure applying mold 31 is lifted down, and then, the liquidfoamable mixture 33 of a polyurethane foam is integrally pressurized andcompressed together with the surface material 2 between the pressureapplying mold 31 and the second cushioning body 10. When this, a gasreaction of the liquid mixture has been completed but the liquid mixtureis still in an elastic flowing condition during a reaction thereof.

In general, by reacting a reactive foamable mixture of a polyurethanefoam, a polyurea foam and the like, a stable foamed body havingexcellent resilient characteristics can be molded. This foamed body isnot easily deformed even though the foamed body is pressurized andcompressed.

However, the mixture is unstable during the reaction and is still in anelastic flowing condition for a certain period after completing a gasreaction so that the mixture can be easily deformed by applying anexternal force. Thus, if the mixture is integrally pressurized togetherwith a second foamed body or a textile material when the mixture is inthe elastic flowing condition, this second foamed body or this materialis fixed on a foamed body of the mixture by entering the mixture in thesecond foamed body or in a part of the textile material, and as aresult, the foamed body of the mixture is integrated in one with thesecond foamed body or the textile material. In addition, acompressibility to the mixture can be controlled, and thus, theresulting foamed body is harder as the compressibility is higher and theresulting foamed body is softer as the compressibility is lower.

Therefore, the first cushioning body having a desired resiliency isformed by transforming the liquid foamable mixture 33 into a solid body,and a back surface of the surface material 2 is fixed on an upper sideof the first cushioning body and the second cushioning body 10 is fixedon a lower side the first cushioning body so that the first cushioningbody can be integrated in one with the surface material and the secondcushioning body. In accordance with the method described in the above,the seat according to the present invention is manufactured.

As mentioned in the above, the central surface portion of the surfacematerial 2 is adjusted to the pressure applying surface 32. Thus, thesecond cushioning body is hardly deformed during the mixture ispressurized and compressed, and the first cushioning body having adesired shape can be molded thereby.

In the embodiment shown in FIG. 4, the liquid foamable mixture isintroduced on the upper surface II of the second cushioning body 10 toform such a layer of the mixture that a part of the layer correspondingto the circumferential body portions of the seat is thin and a part ofthe layer corresponding to the central body portion thereof is thick, sothat the resulting first cushioning body can be soft and can havegenerally the same hardness over the first cushioning body.

Alternatively, if the liquid foamable mixture 33 is introduced on theupper surface 11 of the second cushioning body 10 so that a thickness ofa layer formed by introducing the liquid mixture 33 on the upper surface11 can be the same over the upper surface 11, the compressibility of apart of the layer corresponding to the circumferential body portion ofthe seat is higher than that of a part of the layer corresponding to thecentral body portion thereof, and the circumferential body portions ofthe seat can be harder than the central body portion of the seatthereby.

FIG. 5 shows an embodiment of an alternative method for manufacturing aseat in accordance with the present invention.

As well as in FIG. 4, a pressure applying mold 51 is positioned abovethe second cushioning body 10. A three dimensional shape of the firstcushioning body 6 is defined by a pressure applying surface 52 of thepressure applying mold 51 and the upper surface 11 (which is a surfaceformed by the inner surface 34 of the lower mold 22) of the secondcushioning body 10, as well as the pressure applying surface 32 of thepressure applying mold 31. As a difference between the pressure applyingmolds 51 and 31, step portions 55, 55' are formed on an upper surface ofthe pressure applying mold 51 so that those step portions 55, 55' aresymmetrically provided thereon to set the side surface portion of thesurface material 2.

The surface material 2 is positioned on the pressure applying mold 51.When this, the central surface portion 3 is positioned on the pressureapplying surface 52 of the pressure applying mold 51 and the sidesurface portions 4, 5 stitched with the central surface portion 3 arepositioned on the step portions 55, 55'.

Then, as shown in FIG. 5, a layer of a liquid foamable mixture 53 isformed over a whole of the upper surface 11 of the second cushioningbody 10, as well as the embodiment shown in FIG. 4.

Then, the pressure applying mold 51 is lifted down, and the liquidfoamable mixture 53 is pressurized and compressed together with thesurface material 2 between the pressure applying mold 51 and the secondcushioning body 10 when a gas reaction of the liquid foamable mixturehas been completed but the liquid foamable mixture is still in anelastic flowing condition. Then, the liquid foamable mixture 53 istransformed into a solid body so that the first cushioning body can beformed, and as a result, a back surface of the surface material 2 isfixed on an upper side of the first cushioning body and the secondcushioning body 10 is fixed on a lower side of the first cushioning bodyso that the first cushioning body can be integrated in one with thesurface material 2 and the second cushioning body 10. Then, sidesurfaces of the second cushioning body 10 are covered with the sidesurface portions. Thus, a seat according to the present invention ismanufactured.

FIG. 6 shows an embodiment of an another alternative method formanufacturing a seat in accordance with the present invention.

A pressure applying mold 61 shown in FIG. 6 has basically the sameoutline of the pressure applying mold 51 shown in FIG. 5 and has aplurality of suction holes 66 provided on a pressure applying surface66. The suction holes 66 are connected with an external vacuum pumpsystem (not shown ) to suck the surface material on the pressureapplying surface 62.

In this manufacturing method, firstly, the central surface portion 3 ispositioned on the pressure applying surface 62 of the pressure applyingmold 62 and the side surface portions 4, 5 stitched with the centralsurface portion 3 are positioned on step portions 65, 65', and thesurface material 2 is positioned on the pressure applying mold 61 bydriving the external vacuum pump system to suck the central surfaceportion 3 on the pressure applying surface 62. Such a suction is usefulfor positioning the surface material on the pressure applying surface,in particular, when the surface material is thick or a size of thepressure applying mold is large so that the surface material can not bepositioned along the pressure applying surface. It is desirable that aplastic film is attached on a back surface of the surface material tosufficiently carry out such a suction.

Then, as shown in FIG. 6, a layer of a liquid foamable mixture 63 isformed over a whole of the upper surface 11 of the second cushioningbody 10, as well as the embodiment shown in FIG. 5.

Then, the pressure applying mold 61 is lifted down, and the liquidfoamable mixture 63 is pressurized and compressed together with thesurface material 2 between the pressure applying mold 61 and the secondcushioning body 10 when a gas reaction of the liquid foamable mixturehas been completed but the liquid foamable mixture is still in anelastic flowing condition. Then, the liquid foamable mixture 63 istransformed into a solid body so that the first cushioning body can beformed, and as a result, a back surface of the surface material 2 isfixed on an upper side of the first cushioning body and the secondcushioning body 10 is fixed on a lower side of the first cushioning bodyso that the first cushioning body can be integrated in one with thesurface material 2 and the second cushioning body 10. Then, sidesurfaces of the second cushioning body 10 are covered with the sidesurface portions. Thus, a seat according to the present invention ismanufactured.

In the embodiments shown in FIGS. 5 and 6, a hardness of the firstcushioning body can be partially controlled by adjusting acompressibility, as described in the embodiment shown in FIG. 4. Whilethe surface material is composed by stitching the side surface portionsin those embodiments, a surface material which is united a centralsurface portion with side surface portions can be used. In addition, thesurface material is not limited in a single material. That is, ifnecessary, a composite material which attaches a slab urethane foam on aback surface thereof can be used as the surface material. If the slaburethane foam is attached on the back surface of the surface material,the liquid foamable mixture is not penetrate a textile material of thesurface material when the liquid foamable mixture is pressurized andcompressed. Also, if a plastic film is attached on the back surface ofthe surface material, the liquid foamable mixture is not penetrate atextile material of the surface material when the liquid foamablemixture is pressurized and compressed. Also, a plastic film can beattached on a back surface of the slab urethane foam attached on theback surface of the surface material.

In a seat according to the present invention, a surface material thereofis integrated in one with a cushioning body so that the seat can be softand resilient, and thereby the seat can give a comfortable feeling for aperson who sits thereon. While the surface material is tensioned by aweight of a person who sits on the seat, the surface material isrestored into an original state thereof by the resiliency even thoughthe weight of the person is released, and the surface material can notbe crumpled thereby.

If circumferential and side portions of the seat are harder than acentral portion of the seat, a shape of the seat can be maintained andthe holdability of the seat can be improved without giving anuncomfortable feeling for a person who sits on the seat.

The cushioning body of the seat comprises an upper layer and a lowerlayer, and the upper layer is integrated in one with the lower layer sothat the upper layer can be underlain by the lower layer which does notdirectly contact with a person who sits on the seat. Thus, a weight of aperson who sits on the seat can be supported and a shape of the seat canbe maintained by hardening the lower layer without giving anuncomfortable feeling for the person.

Only one member as the surface material which contacts with a person whosits on the seat can be molded, so that it is unnecessary to cut intoseveral members of the surface material, and parts and materials of theseat can be simplified thereby, and the manufacturing process is alsosimplified so that the manufacturing cost can be reduced.

Because each cushioning body is united with each other, an assemblingwork for connecting each cushioning body is eliminated, and a work formanufacturing a seat can be reduced thereby.

What is claimed is:
 1. A method for manufacturing a seat comprising asurface material and a cushioning body integrated in one with saidsurface material, wherein said cushioning body has a shape generallycorresponding to an outline of the seat and is composed of a firstcushioning body and a second cushioning body which underlies said firstcushioning body, comprises steps of:introducing a liquid foamablemixture for forming said first cushioning body on a surface of thesecond cushioning body; facing at least a part of a back surface of saidsurface material to said liquid foamable mixture introduced on saidsurface of said second cushioning body; and pressurizing and compressingsaid liquid foamable mixture, which is introduced on said surface ofsaid second cushioning body, together with said surface material betweensaid second cushioning body and a pressure applying mold having a shapecorresponding to a shape of a central portion of said seat andpositioned above the surface material, when a gas reaction of saidliquid foamable mixture has been completed but said liquid foamablemixture is still in an elastic flowing condition.
 2. A method of claim 1wherein said step of facing is carried out by placing said liquidfoamable mixture, which is introduced on said surface of said secondcushioning body, between said surface material and said secondcushioning body so that said second cushioning, body can be covered withsaid surface material, andwherein said surface material comprises acentral surface portion and side surface portions continued from saidcentral surface portion, said central surface portion being integratedin one with said first cushioning body, sides of said second cushioningbody being covered with said side surface portions.
 3. A method of claim1, wherein said surface material comprises a central surface portion andside surface portions continued from said central surface portion, saidcentral surface portion being integrated in one with said firstcushioning body, sides of said second cushioning body being covered withsaid side surface portions.
 4. A method of claim 1, wherein a hardnessof said first cushioning body is different from a hardness of saidsecond cushioning body.
 5. A method of claim 1 wherein said first andsecond cushioning bodies are molded of a reactive foamable resin.
 6. Amethod of claim 1, wherein said step of pressurizing and compressingincludes a step of partially adjusting a compressibility applied forsaid liquid foamable mixture when said gas reaction has been completedbut said liquid foamable mixture is still in said elastic flowingcondition, to partially control a hardness of said first cushioningbody.
 7. A method of claim 6 wherein said step of partially adjustingsaid compressibility comprises steps of:partially adjusting a spacedefined between said pressure applying mold and said second cushioningbody; introducing said liquid foamable mixture on said second cushioningbody so that a thickness of a layer formed by introducing said liquidfoamable mixture can be the same over said second cushioning body; andpressurizing and compressing said layer.
 8. A method of claim 1 whereinsaid surface material is selected from the group consisting of a textilematerial of a woven fabric, a knitted fabric, a leather, a syntheticleather and a PVC leather.
 9. A method of claim 8 wherein a slabmaterial of a slab urethane foam is provided on a back surface of saidsurface material.
 10. A method of claim 8 wherein a plastic film isprovided on a back surface of said surface material.
 11. A method ofclaim 8 wherein a slab material of a slab urethane foam is provided on aback surface of said surface material and a plastic film is provided ona back surface of said slab urethane foam.
 12. A method formanufacturing a seat comprising a surface material and a cushioning bodyintegrated in one with said surface material, wherein said cushioningbody has a shape generally corresponding to an outline of said seat andis composed of a first cushioning body and a second cushioning bodywhich underlies said first cushioning body, comprises stepsof:introducing a liquid foamable mixture for forming said firstcushioning body on a surface of said second cushioning body; positioninga central surface portion of said surface material in a pressureapplying mold which has a shape corresponding to a shape of a centralportion of said seat and is positioned on said second cushioningmaterial; facing said central surface portion positioned in saidpressure applying mold to said liquid foamable mixture introduced onsaid surface of said second cushioning body; and pressurizing andcompressing said liquid foamable mixture, which is introduced on saidsurface of said second cushioning body, between said second cushioningbody and said pressure applying mold which positions said surfacematerial, when a gas reaction of said liquid foamable mixture has beencompleted but said liquid foamable mixture is still in an elasticflowing condition.
 13. A method of claim 12 wherein said surfacematerial comprises a central surface portion and side surface portionscontinued from said central surface portion, said central surfaceportion being integrated in one with said first cushioning body, sidesof said second cushioning body being covered with said side surfaceportions.
 14. A method of claim 12 wherein a hardness of said firstcushioning body is different from a hardness of said second cushioningbody.
 15. A method of claim 12 wherein said first and second cushioningbodies are molded of a reactive foamable resin.
 16. A method of claim 12wherein said step of pressurizing and compressing includes a step ofpartially adjusting a compressibility applied for said liquid foamablemixture when said gas reaction has been completed but said liquidfoamable mixture is still in said elastic flowing condition, topartially control a hardness of said first cushioning body.
 17. A methodof claim 16 wherein said step of partially adjusting saidcompressibility comprises steps of:partially adjusting a space definedbetween said pressure applying mold and said second cushioning body;introducing said liquid foamable mixture on said second cushioning bodyso that a thickness of a layer formed by introducing said liquidfoamable mixture can be the same over said second cushioning body; andpressurizing and compressing said layer.
 18. A method of claim 12wherein said surface material is selected from the group consisting of atextile material of a woven fabric, a knitted fabric, a leather, asynthetic leather and a PVC leather.
 19. A method of claim 18 wherein aslab material of a slab urethane foam is provided on a back surface ofsaid surface material.
 20. A method of claim 18 wherein a plastic filmis provided on a back surface of said surface material.
 21. A method ofclaim 18 wherein a slab material of a slab urethane foam is provided ona back surface of said surface material and a plastic film is providedon a back surface of said slab urethane foam.
 22. A method formanufacturing a seat comprising a surface material and a cushioning bodyintegrated in one with said surface material, wherein said cushioningbody has a shape generally corresponding to an outline of the seat andis composed of a first cushioning body and a second cushioning bodywhich underlies said first cushioning body, comprises stepsof:introducing a liquid foamable mixture for forming said firstcushioning body on a surface of said second cushioning body; positioninga central surface portion of said surface material in a pressureapplying mold, which has at least one suction hole and has a shapecorresponding to a shape of a central portion of said seat, by suckingsaid central surface portion through said suction hole; facing saidcentral surface portion positioned and sucked in said pressure applyingmold to said liquid foamable mixture introduced on said surface of saidsecond cushioning body; and pressurizing and compressing said liquidfoamable mixture introduced on said surface of said second cushioningbody between said second cushioning body and said pressure applying moldwhich positions said surface material by sucking, when a gas reaction ofsaid liquid foamable mixture has been completed but said liquid foamablemixture is still in an elastic flowing condition.
 23. A method of claim12 wherein said surface material comprises a central surface portion andside surface portions continued from said central surface portion, saidcentral surface portion being integrated in one with said firstcushioning body, sides of said second cushioning body being covered withsaid side surface portions.
 24. A method of claim 12 wherein a hardnessof said first cushioning body is different from a hardness of saidsecond cushioning body.
 25. A method of claim 22 wherein said first andsecond cushioning bodies are molded of a reactive foamable resin.
 26. Amethod of claim 22 wherein said step of pressurizing and compressingincludes a step of partially adjusting a compressibility applied forsaid liquid foamable mixture when said gas reaction has been completedbut said liquid foamable mixture is still in said elastic flowingcondition, to partially control a hardness of said first cushioningbody.
 27. A method of claim 26 wherein said step of partially adjustingsaid compressibility comprises steps of:partially adjusting a spacedefined between said pressure applying mold and said second cushioningbody; introducing said liquid foamable mixture on said second cushioningbody so that a thickness of a layer formed by introducing said liquidfoamable mixture can be the same over said second cushioning body; andpressurizing and compressing said layer.
 28. A method of claim 22wherein said surface material is selected from the group consisting of atextile material of a woven fabric, a knitted fabric, a leather, asynthetic leather and a PVC leather.
 29. A method of claim 28 wherein aslab material of a slab urethane foam is provided on a back surface ofsaid surface material.
 30. A method of claim 28 wherein a plastic filmis provided on a back surface of said surface material.
 31. A method ofclaim 28 wherein a slab material of a slab urethane foam is provided ona back surface of said surface material and a plastic film is providedon a back surface of said slab urethane foam.